Art of electric smelting.



E'. R. TAYLOR. AI1.I,0I' ELECTRIC SMELTING. APPLICATION FILED MAR Patented Oct. 26, 1,909."

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attaining l n E.. R. TAYLOR. VART 0F ELEGTRIG SMELTING. lAPPLICATION FILED M.A1`\',.3l 1909.

Patented 001;. 26, 1909. ,4 SHEETS-SHEET 2.

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E. R. TAYLOR.

ART 0F ELECTRIC SMELTING.

APPLICATION FILED- MAR. 3, 1,909.

Patented 0015.26, 1909.

4 SHEETS-#SHEET 3.

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E. R. TAYLOR. ART 0F ELECTRIC SMELTING. APPLIGATION FILED MAR.s,19oe;-"\

938,352. l n Y Patented Osma-'1909.

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narran sra'rns EDWARD R. TAYLOR, OF PENN YAN, -NEW YDRK.

ART OF ELECTRIC SMELTING.

Specification of Letters Patent. Patented Oct.. 26, 1909.

Original application filedr June 12, 1908, Serial No. 438,115. Divided and this application-filed March 3, 1909.

' Serial No. 481,121.

To all 'whom 'it may concern:

4Be it known that I, EDWARD R. TAYLOR, a citizen of the United States of America, and

a resident of Penn Yan, in the State of New York, have invented a new and useful Im. provement in the Art of Electric Smelting, of which the following is a specification.

This invention relates primarily to the electric smelting of oXid iron ores by a continuous process; but novel features of the process may be used for effecting other reactions and reductions.

The present invention consists 1n the 1m- Vproved process of smelting oxid iron ore or similar metallurgical material in an electric furnace hereinafter described, and' certain novel featuresthereof, as more particularly set forth in the claims hereto appended.

The inventionis in'part additional to the l Improvement in the art of producing chemicals in electric furances 'set forth in my specification forming part of United States Letters Patent No.' 702,117, dated June 10, 1902.

The objects of the present invention common thereto and to said patented improvement include the protection of'horizontal or substantially horizontal electrodes against excessive wear, and the regulation of they electric action within the furnace, by means of fragmentary oonductingor resistance re ulating material, fed by gravity upon said electrodes and between the same; the interception and utilization to the utmost of heat that would otherwise be lost by radiation; and the avoidance of the cooling of the more highly heated inner part of the furnace or heat zone, in continuous reactions and reductions, by the sudden introduction of cold material, so as to insure the continuity of the operation.

Other objects common to said patented improvement and the present invention are to utilize in an effective lmanner the alternating or two-phase electric current, and to provide for varying the paths of the electricity through the charge within the Working chamber so as to prevent the formation .of piers of the less fusible ingredients of the charge or to burn out such piers should they accidentally be formed.

Other objects, including most of those hereinafter stated, are common to the present improvement and to my improvement in electric smelting furnaces more particularly described and claimed in the specification forming part of my application for patent filed June 12,1908, Serial No; 438115; the application for patent of which mypresent specification forms part, being a relnace, and especially to .keep the material of the charge between the electrodes from'becoming so conductive of electricity as to.'

reduce the resistance of the furnace below practicable working limits.

Other objects are the separation of the ore in the four quarters of a two-phase furnace having two pairs of horizontal or inclined main electrodes, hereinafter referred i to in common as horizontal, arranged in vertical planes at right angles to each other, so as to keep the same separate, and thus to facilitate the manipulation of the ore Within the furnace; to provide for employing a large proportion of fine ore, such as cannot be smelted in a blast furnace because ofits liabilityy to. be blown out of the furnace by the blast; to provide for feeding iine and coarse ore downward in a stack furnace in separate vertical or' substantially vertical' short circuits; to provide for admitting successive small quantities'of ne ore into the outer edges of the coarse ore columns in order to gradually bring the hottest of the fine ore in toward the center of the furnace, and to relieve the stress ofstoking to that eX- tent; to provide for feeding suitable car-` bonaceous material, preferably either coke or charcoal, in acentral column, and for utilizing lateral wings of such coke column, as it is hereinafter termed, to separate the columns of coarse ore; to utilize such coke column as a resistance conductor between secondary electrodes located at v,the

bottom and top of the furnacerespectively; to provide in this way for starting the furnace with facilityy by the interaction of said secondary electrodes and said coke column; to keep the carbonaceous material of the charge incandescent to a greater height than has heretofore been practicable; to vary the height of such incandescence at will; to determine thus the percentage of carbon, for example, in the reduction of iron, so as to produce pig iron or steel as may be desired; to insure the reduction of ore to metal, to as considerable an extent as may bepossible, in the fine ore before it reaches the heat zone, and to utilize the heat between said horizontal electrodes for streams or globules of fluid metal asthey trickle downward, so that they shall carry with them into the hearth sufficient heat to keep the meta-l in the hearth in a fluid condition.

Another object of the invention is to oxidize accumulations of carbon or other oxidizable materials which may at times form to an undesirable amount and interfere with the regular working, of the furnace.

Other objects peculiar to the present improveinent and said companion improvement in electric smelting furnaces relate especially to the production in an electric furnace of iron or steel, hereinafter referred to in common as metal, from iron ores consisting of or containing sesquioxid of iron, F e203, or magnetic oxid, Fe304, or other forms of iron oxid adapted for like treatment. Sesquioxid of iron, for example, at a suilicient but low temperature, in contact with carbonio oxid gas also at a low but suiiiciently high temperature, undergoes substantially the following reaction, that is to say: 1(Fe2O3){-3(CO)=2Fe+3(CO2).

In the production of iron in a blast furnace the above reaction is usually completed before the material reaches the high teinperature of the fusion zone. To accomplish this reaction in the electric furnace, as heretofore constructed, has been a matter of uncertainty and difficulty; and it is one object of the present invention to furnish conditions whereby the above reaction will be accomplished in the regular order of the descent of the material from the feed hopper to the heat zone. In the first heating-up of an electric furnace of this kind, as the coke, charcoal or other carbonaceous material is brought to incandescence by the resistance it offers to the passage of the current, any ox en within reach will be absorbed, with t e ormation of carbonio acid (CO2), which gasin the presence of an excess of incandescent carbon speedily becomes reduced to carbonic-oxid gas (CO); one molecule of the Carbonicacid becoming two molecules of the carbonio-mild gas. This latter as then comrng in Contact with the oxid o iron, in any superheating y the of its oxid forms, at a sufficiently high temperature, absorbs oxygen from the ore, with the reduction of 'the ore to metal, and the formation of one molecule of carbonio acid for each molecule of carbonic-oxid gas. If the .carbonio acid thus formed can again .be

brought into contact with incandescent carbon, and the resulting carbonio oxid gas again brought into contact with iron ore, the same react1ons above described will repeatedly take place; and another object of this invention is to so circulate these two gases as to repeatedly bring the carbonio oxid gas as quickly as practicable after its formation into contact with iron ore in its proximity, and afterward, as soon as possible thereafter, to bring the carbonio acid thereby produced into contact with incandescent carbon, and to repeat the cycle of these reac tions until the ii'nal gas passes out of the furnace at its top.

Other objects will beset forth in the general description which follows.

Four sheets of drawings accompany this specification as part thereof.

Figures l and 2 represent axial vertical sections in different planes through an electric smelting furnace, illustrating the improved smelting recess; Fig. 3 is a plan view of the top of) the furnace above its top plate, indicating by lines A-B and C-l) the planes of Figs. l and 2, respectively; Fig. 4l represents a detail sidevview of one of the stoking screws enlarged from Fig. 2; and Figs. 5, `Gand 7 are diagrams representing the paths of the electric current under different conditions.

Like reference characters indicate like 'parts in all the figures.

The present improvement in the art of electric smel'ting is preferably and conveniently carried into effect withinand by means of the'electric smelting furnace represented by said drawings, and may be described in connection therewith as follows: The furnace so represented is of a stack form; its internal structure, a, being builtof suitable brick or the like within a metallic shell, Z), of iron or steel, hereinafter referred to as iron; a layer, c, of a suitable non-conductor of electricity, such as asbestos, being interposed between the internal structure l and the shell Z) throughout. The top plate, d, of the shell b and of the furnace is' conveniently horizontal, and'is provided with feeding hoppers, e, f, g and L, best shown in Fig. 4, which are so shaped and so united with each other and with the top plate by braces, stays and angle irons,represented rcspectively at l, 2 and 3, as to form a truss by which the subjacent top-plate is stiii'ened against sagging. The respec'tiviF Hoppers, e, fhg and 7L communicate with the upper ends of flue-sha extend downward within the internal strucd' passages, z', j, and Z, which 4appropriated to the principal charge of ore,

.hereinafter referred to as the coarse ore, Vwhich is thus divided into several distinct columns. Another set of said hoppers and passages, g and la, external to said coarse-ore passages, are appropriated to fine ore,which may be of that description which is too fine forl reduction in a blast furnace, and which isutilized in this arrangement, not only to feedfine ore. into the charge, as hereinafter more particularly set forth, but also and primarily to conserve the heat of the furnace by intercepting and utilizing heat that would otherwise escape by. radiation and by being conducted outward, and t-o carry the same back into the working chamber so as to protect,the iron shell of the furnace against ,excessive heat, and to utilize such radiant or outwardly directedheat in thereduction of theI ore` The tine-orel passages/c are divided into inner and outer passages by hollowlwalls forming a gas space, m, Fig. 2, .within each wall, open'at bottom? and in direct communication with said coarse-Ore passages j and with the working'chamber, n, by way of outwardly `flaring gas tubes, 0 hereinafter more particularly described. The. outerl fine-ore passages, marked c, communicate .with the working ychamberat their lower ends only andarerlocated,peripherally, as shown in Fig. 2, -so that-the body of tine ore within them may, becas cool landas continuous as maybe practicable, with reference to intercepting 'fand4 utilizing outwardly directed heat. rllhe inner fine-ore passages, ic are provided with bafieplates, p, Fig. 2, preferably V-shaped in tcross section, vand arranged with the apex uppermost lso vas to. retard the How of the ne lcreto asuflicient extent without being subjected to breaking strains, and more particularly to form suitablyv distributed spaces throughout the body of fine ore.

From yeach of thesespaces an opening, p', Fig. 2, extends inward-through the wallof the working chamber n, and affords a discharge formore or less of the fine ore as it reaches that point into the outer edges of the coarse-ore columns, so as to gradually mix the two as they approach the heat zone, and

to gradually bring the hottest of the fine ore inward toward the center of thefurnace'and thus ,to reduce the need of striking.

The central hopper e and the passage iv extending vertically therefrom are appropriated -to suitable dry carbonaceous material, which 'may consist wholly or in part of charcoal or coke and is hereinafter referred to as coke. The coke column so formed is intended to preserve its identity from top to bottom of the furnace in the initial charge, and from the top to the fluid contents of the hearth when the furnaceis in operation, as in Figs. l and 2. Said coke passage a' is formed by a central circular wall at thetop of the furnace, and this wall is supported by partition walls in the form of flying buttresses, arranged in pairs around said central wall, and forming between them where their inner edges are exposed below` said circular wall, a wingshaped passage, a", Fig. 1, in communication with said central passage z', above each 'of the main electrodes, g, r, s, and t, so that the coke may spread laterally in the form of wings between and below said partition walls, and extend the separation of the columns of-coarse ore as hereinafter described. The other four of said hoppers, shown at la in Figs. l and 3, and the peripheral passages, Z, leading downward therefrom, are appropriated to the feed of resistance regulatingv material adapted to flow downward by gravity and tofprotect the main electrodes and regulate the conductivity of the charge at the heat zone 'as set forth in the previous specification hereinbefore referred to. IA

up of relatively small carbons, and securely united with ample electriccontact to a metallic stein, 6, preferably of aluminum. Each of these electrode stems extends outward through a water-cooled Vstuiiing box, 7 which is mounted on a face-plate, 8, covering an opening through which the body of the electrode may be introduced and withdrawn, and detachably secured to the iron shell I). Insulation against the leakage of electricity Ais introduced between the electrode stem and the gland of the stuiiing box, and between the face-plate land iron shell, either or both.

Secondary electrodes, o and w,are located respectively at the bottom and to of the furnace; the bottom electrode, o, iaving a carbon body, 9, which forms a lining for the hearth u of the furnace, and is connected with a dependingcentral metallic stem, 10. Suitable provision is made for coolingthe electrode stern 10, as indicated by the water circulating pipes 18 and 19,7Eig.1, the details of which may be of any known or irnproved description. The other electrode stems may obviously be cooled in like Inanner. Saidelectrode stem 1G protrudes through a water-cooled stuffing box, 20, mounted on a face plate, 2l, which is bolted 'lio top electrodes proper, are `supported subto-the bottom of the furnace, so as to be detachable, and when detached ex oses an opening, 22, through which the cndp disk 10 of the stem is introduced and withdrawn.

The secondary electrodes, tu, at the top of the furnace, are preferably four in number, located above the respective main electrodes g, 1', s and t. The metallic stem, 27, of each of these electrodes extends upward through a water cooled'stutling box, 28, on the top plate (Z as shown in Figs. l and 3. The carbon bodies of the top electrodes w,-or the jacently within'rectangular pocket-s, 29, Fig. l, formed in the walls of the central coke passage z', so that the face of the carbon body of each of these electrodes is substantially flush with the inner surface of said wall, and in contact with the charge of coke through which the electric current passes from the bottom electrode u to the top electrodes w; the latter being of one polarity.

The two sets of electrodes, that is to say the main electrodes, g, r, s, t, and the secondary electrodes, o, w, are preferably connected electrically with different dynamos; and the latter are prefe-rably of the two` phase or alternating type, for the main electrodes, at least. The bottom electrode v forms the lining, as aforesaid, of a health u, which is made of ample capacity and is located immediately beneath the main electrodes g, r, s, and t, and provided with an outlet, 30, through which to run oif the tuid metal, and an outlet, 31, at a higher point, for molten slag. The hearth portion of the furnace is suspended from an annular metallic sill, 32, which may rest upon columns or the like in customary manner, and the depending portion of the hearth is provided with a water jacket, 23, provided with suitably located inlet and outlet' connections, 34 and 35, Fig. 1. i

An annular gas chamber, 3G, Figs. 1 'and 2, at the top of the furnace, communicates freely with the coarse-ore and coke passages, and with the intermediate passages for fine ore and regulating material, and discharges through an outlet pipe, 37, Figs. l and 3.

For circulating the gases within the furnace, with reference to promoting the reduction' of oxid iron ore in the manner hereinbefore described, and gas spaces m formed within the several fine-ore sections of the furnace, as shown in F ig. 2, communicate as already mentioned with tubes o. These tubes o extend through the inner fine-ore' passages (if.) from the coarse-ore passages j, outward into curbs, 38, which project in-A ward to such gas spaces m from outside the furnace:l and rotary blowers, 39, in the form of electric fans, are located within the outer ends of said tubes and driven b electric lfrom opposing one another.

motors, af, attached to the iron shel of the furnace; the operation being to draw through the ore into said gas spaces m the carbonio oXid gas, CO, formed at and inv the Vicinity of the heat zone, and to force the resulting carbonio acid, CO2, through the coarse ore into the central column of hot coke, by which it is again reduced to carbonic oXid gas, so as to render possible the repetition of this reaction sufficiently to reduce the fine ore to a considerable extent as it escapes from beneath the baille plates'p, through the openings p, on its way to the heat zone and before reaching the hottest part of the furnace. The blower tubes I0 are so located as lto keep the blowers cu-39 The columns of coarse ore and coke within the working chamber of the furnace are separated initially at top by partitions formed as already indicated by iiying buttresses sprung between the wall of the working chamber n and the central circular wall within which the top electrodes w are located. Compare F l and 2. The initial separation of the columns thus insured perpetuates itself downward, within the working chamber a, as indicated in Figs. l and 2, where the charge of the furnace is represented in the plane of section.

The regulating material descending by gravity through its passages'Z, as shown in Fig. l, tends by its greater weight to feed itself beneath the superjacent wmgs of the coke column, upon and between the main electrodes, g, 1', s, t, as shown in this figure; and the several streams may be manipulated, if desired, to increase or lessen their effect in regulating the operation of the furnace, by means of suitable stokers provided with insulated handles and introduced through stoke holes 4, Fig. l. The fine-ore passages v-c and gas spaces m, terminate at bottom in open ends within arched recesses, y, Fig.

2. The ine ore thus released tends to fall inward to a greater or less extent as indicated in Fig. 2, and any particles which may enter with 'the gases into the gas spaces m are immediately discharged therefrom soas to keep said spaces clear.

To insure the inward feed of the ore to a sutlicient extent, suitable stoking means are provided beneath the several tine-ore passages c. Such means may consistof stoking screws, z, Fig. 2 and Fig. 4. The fine ore, descending by gravity to the plane of these stoking screws e is there forced inward toward the heat zone, as represented in Fig.

2, carrying with it and intermin ling with more or less of the coarse ore. T e stoking screws .alare rotated for this purpose by means of worm gearing, 40, which may be driven by hand cranks or by electric motors. Compare Figs. 2 and 4. The screws e have their main bearings in water-cooled stumug boXes,'4l, and/outer bearings within yokes, 42, attached to the face plates, 43, which passage of the electric current outward through the screws;A The screws .2 may'be of iron and the insulating sections 45 of any suitable material that will resist the furnace heat. as well as the electric currents, as for example a suitable asbestos or' asbestos-andmica compound. The inlet and outlet watery connections ofv each stulling box 41 and each water-cooled frame 44 are represented respectively in Fig. 4 at 47--48 and 49-50;

The openings capped by the faceplates/13 and through which the stoking screws are inserted endwise into the' furnace and with-.f drawn for renewal or 'repairs are repre-- sented at' 51 in Fig. 4. l i

For the purpose of oxidizing fortuitous accumulations of carbon or other oxidiziablel' materials at or in the proximity of the focusv of the furnace, the inner and'outerstems of the working screws shown at .e are provided with axial passages, 52, Fig. 4, and the outer stems 46 are connected by swivel couplings, 53, with hose or pipes, 54, through which air or other suitable oxidizing material may be blown into the center ofthe working chamber n at will.

One or more man holes, 57,Fig. 2, suitably capped, and conveniently located beneath one or more of the stoking screws z, provide for entering the 'furnace after it is emptied and cooled for the renewal of re-V pair of the electrodes and other like work, and may also be utilized in arranging the charge preliminarily.' Ink preliminarily charging the furnace, the hearth u is filled with coke, and a column of coke is built up within the working chamber n surrounded by coarse ore to a sufficient height'to insure the completion of a continuous coke column extending from the bottom electrodec to a point more or less near the upper ends of the top electrodes/w. Simultaneously, after the plane of the main electrodes, g, r, s, t, is reached, fine ore may be fed in through the fine-ore hoppers, g, until the fine-ore passages, c, k, are filled or substantially filled. The passages, l, for regulating materiell, above the several main electrodes, g, r, s, t, may be filled at the same time or subsequently, and the streams of regulating material may be suitably directed over and in. contact with the main electrodes, as shown in Fig. 1.

The electric current is turned on, lirst i through the secondary electrodes c and fw, as illustrated diagrammatically ,by Fig. 5,

y'and through the intervening column of coke, which is thus rendered lncandescent. The

current is then turned on through the main electrodes, g, 1"., s, t, and its supply to both sets from different dynamos as aforesaid, may be simultaneous as illustrated diagrammatically by Fig. G. The current may thus be passed through the charge by way of all the electrodes' throughout the reducing operation, or the secondary. electrodes, @410, may be used only occasionally as required. The height to which the central 'cokecolumn is kept incandescent may be determined by passing fmore or less ycurrent therethrough by way of'said secondary electrodes as required, and that in lturn determines the proportion of earbcm'fin the molten'metalas it reaches the lyheartlgfPand facilitates producing either pig Vironor vSteel at will'. 4The gas circulating blowers, :i2-39, are lstarted' as soon as the coke column is incandescent, so as to insure the conversion of theca-rbon-oxid gas formed in the Vicinity of the heat zone into carbonio acid, land the conversion of'the latter into carbonic-oxid gas again, and so on alternately as above described. 4Suitableluxes are added to the several columns of ore and possibly to the coke, as may be required, and the supply of materials by way of the several hoppers, e, f, g, 71., at the top. of the4 furnace, is kept up so as to render the operation of the furnace substantially continuous.

" Stoking at the Stoke holes 4, Fig. 1, is

resorted to occasionally as may be required to render the operation 'of the main electrodes, g, 1', s, substantially uniform; and the stoking screws a are operated from time to time as may be required to regulate the feed of the fine ore inward to the heat zone. The fluid met-al is runA ofi from time to time or continuously through the tap hole, 30, Fig. 1, and the molten slag through its outlet 31, Fig. 1. The discharge of gas through the pipe 37 at the top of the furnace may be continuous, and' may, if desired, be promoted by an exhaust fan; the gasbeing' stored, for use in engines or otherwise, i'n known or improved ways.

The electric connections may include suitable switches for varying the How of the current through the main electrodes, g,r,8, t, as illustrated by Fig. l2 of said Patent No. 702117, dated June 10, 1902; and in like manner provision may be made for disconnecting the main electrodes from their normal source of supply and throwing them into circuit with the bottom electrode c, as illustrated by Fig. 7, in order to melt out the contents of the hearth u after temporarily suspending the operation.

Suitable carbonaceous material will in most cases be mixed with the ore, and other mixtures may obviously be fed into the working chamber through the several hoppers at thev top of the furnace to produce allo-Qs. or otherwise to regulate or vary the product of the furnace. For example. large pieces or chunks of electrode carbon may be fed into the central hoppers e occasionally or systematically, so as to become parts of the coke column and to feed slowly downward therein, with reference to their accumulation to a sutiicient extent between the main electrodes, q, r, s, t, to hold back one or more of the materials for reduction, and to insure propen, conductivity without obstructing the trickling of streams of the molten metal downward between the electrodes into the hearth'.

The electric smelting furnace shown in the dra-wings accompanying my present speciication is more fully described and shown together with modifications thereof in the specification forming part of my application for patent, Serial No. 438115, tiled June l2, 1908, hereinbefore referred to and the drawings accompanying the same, and forms no part of the invention hereinafter claimed.

Having thus described said improvement, I claim as my invention, and desire to patent under this specification:

l. The method of charging an electric smelt-ing furnace of the stack type having horizontal electrodes, which consists in maintaining within the furnace a central column of dry carbonaceous material, feeding material for reduction downward in separate columns at the sides of said central column and in contact the rewith,.and further separating said columns of material for reduction by feeding carbonaceous material downward between them and in Contact therewith above the several electrodes.

Q. The method of charging an electric smclting furnace of the stack type having horizontal electrodes, which consists in maintaining within tlie `furnace a central column of dry carbonaceous material, feeding material for reduction downward in separate columns at the sides of said central column and in contact therewith, and furtherseparating said columns of material for reduction by feeding carbonaceous material downward between them and in contact therewith above the several electrodes, such separating material consisting partly of wings of said central column and partly of streams of harder and heavier resistance regulating ma terial.

3. The method of charging an electric smeltin'g furnace of the stack type having horizontal electrodes, which consists in maintaining within the furnace a central column of dry carbonaceous material, feeding coarse ore downward in separate columns at the sides of said central column and in contact therewith, simultaneously feeding fine ore downward in separate columns external to said coarse ore columns, and further separating said ore columns by feeding carbonaceous material downward between them above the several electrodes.

4. The method of charging an electric smelting furnace of the stack type having horizontal electrodes, which consists in maintaining within the furnace a central column of dry carbonaceous material, feeding coarse ore downward in separate columns at the sides of said central column and in contact therewith, simultaneously feeding fine'ore downward in separate columns external to said coarse ore columns, further separating said ore columns by feeding carbonaceons material downward between them above the several electrodes, and mixing the hottest of the line ore with the coarse ore on their way to the plane of the electrodes.

5. The method of smelting electrically conductive material in an electric furnace of the stack type having horizontal electrodes, which consists in feeding a column of carbonaceous material downward into the space between the electrodes and wings of said column above the respective electrodes, introducing the material for reduction in connection with suitable iuXes at the sides of said column and wings and feeding the same by gravity within the working chamber in separate columns which descend at the sides of said column and wings and at the sides of said electrodes but suiiiciently removed therefrom to prevent the reduction of the material to a short-circuiting mass between the electrodes, and passing a suitable current through the charge by way of said electrodes.

6. The method of smelting electrically conductive material in an electric furnace of the stack type having horizontal electrodes arranged in pairs at right angles to each other, which consists in .feeding downward a central column of earbonaceous material between the electrodes and wings of the same above the several electrodes, and feeding downward the material for reduction in cols umns separated from each other by the carbonaceous material and confined to the several quarters of the furnace, whereby the reduction of the conductive material to a short-circuiting mass between the electrodes is prevented; a suitable current being passed through the charge by way of said elec trodes. 7. 'in' there'duction of electrically conductive materai by smelting in an electric furnace of the stack type having horizontal electrodes, the method of preventing the formation of a pasty mass between the electrodes andl vthereby short-circuiting the,cur rent, which consists in feeding a column of carbonaceous material downward between said electrodes, and feeding in therewith large pieces of relatively hard and conductive cabonaceous material adapted to bridge the space between the electrodes and hold back the material for reduction.

8. In the reduction of ores by smelting in an electric furnace of the stack type having i central column of carbonaceous material horizontal main electrodes and secondary electrodes at top and bottom, the method of preventing the formation of a pasty mass between the main electrodes and thereby short-circuiting the current, which consists in feeding a column of carbonaceous material downward between said main electrodes, expanding the heat zone upward by way of said column by passing a suitable current through said secondary electrodes, and thus insuring the reduction of re to metal above said main electrodes.

9. In ,the reduction of ores by smelting in .anelectric furnace of the stack typehaving horizontal main electrodes and Secondary electrodes at top and bottom, the method of preventing the formation of a pasty mass between the main electrodes and thereby short-circuiting the current, which consists in feeding a column of carbonaceous material downward between said main electrodes and expanding the heat zone iupward by way of said column by passing a suitable current through said secondary electrodes, reducing ore to metal in the form of globules above the plane of said main electrodes, and causing the` same to trickle downward between said main electrodes.

10. In the reduction of ores by smelting in an electric furnace of the stack type having horizontal main electrodes and secondary electrodes at top and bottom, the method of prevevnting the formation of a pasty mass between the main electrodes and thereby short-circuiting t-he current, which consists in feeding a column of carbonaceous material downward between said main electrodes and expanding the heat zone upward by way of said column bypassing a suitable current through said secondary electrodes, reducing ore to metal in the form of globules above the plane of said main electrodes, causing the same totrickle downward between said mainelectrodes, superheating the same at this point by a sufficient current passin through said'main electrodes, and

collectingthe metal in superheated oondi' tion in a subjacent hearth.

1l. In the reduction of ores by smelting in an electric furnace of the stack type having horizontal electrodes, and in which the material for reduction is fed-downward Within the working chamber'in columns by gravity,

the method of removing fortuitous accumulations of carbon or other oxidizable material, which consists in the introduction of suitable oxidizing material into the center of the furnace as-needed.

12. In the reduction of oxid ores by smelt# ing in an electric furnace of the stack type having horizontal main electrodes immediately above its hearth and secondary'electrodes at the top of the furnace, the process which consists an maintaining a gravity fed contacting with said top electrodes and extending downward therefrom, feeding the I ore downward by gravity at the sides`of said column of carbonaceous material and in communication therewith and passing suitable currents of electricity through the charge by way of said main electrodes, and through said column of carbonaceous Inaterial by way of saidsecondary electrodes.

13. In the reduction of oxid ores by smelting in an electric furnace of the stack type having electrodes at top and bottom, the process which consists in maintaining within the furnace a gravity fed central column of carbonaceous material which forms a resistance conductor between said top and bottom electrodes, feeding the ore downward by gravity at the sides of said column of carbonaceous material and in commu-nication therewith, passing a suitable current of electricity 'through said electrodes and said column, producing carbonio oXid gas by reducing said column of carbonaceous mater'ial to incandescence,l bringing said gas into contact with contiguous ore continuously forits reduction to metal, and passing the resulting carbonio acid continuously into contact with the incandescent column of carbonaceous material.

14. In the reduction of oXid ores by smelting in an electric furnace of the stack type.

having horizontal main electrodes and secondary electrodes at .top and bottom, the process which consists in maintaining a gravity-fed central column of carbonaceous material which forms a resistance conductor between said top and bottom electrodes, feeding the ore downward by gravity at the sides of said column of carbonaceous material, passing suitable currents of electricity through said main electrodes and said secondary electrodes respectively, producing carbonio oxidlgas by reducing said column of carbonaceous material to incandescence, bringing said gas into contact with contiguous ore vfor its reduction to metal, and afterward as quickly as practicable passing the resulting carbonio acid into contact witht-he incandescent column of carbonaceous material again.

15. In the reduction of oXid ores by smelting in an electric furnace of the stack type having horizontal main electrodes and secondary electrodes at top and bottom, the process which consists in maintaining a gravity-fed central column of carbonaceous material which forms a resistance conductor between said top and bottom electrodes, feeding the ore downward by gravity at the sides of said column of carbonaceous material, passing suitable currentsthrough said vmain electrodes and said secondary electrodes respectively, producing carbonio oXid gas by reducing said column of carbonaceous electrodes and secondary electrodes at topand bottom, the process which consists in feeding the sesquioxid and suitable carbonaceous .material downward by gravity, passing a suitable current through saidsecondary electrodes to render the column of carbonaceous material incandescent and thereby producing carbonio oXid gas, lbringing said gas into contact with the sesquioxid for its reduction into metal above the plane of said main electrodes, afterward as quickly as practicable passing the resulting carbonio acid into contact with the incandescent carbcnaceous material again, and superbeating the metal as it trickles downward between said main electrodes into the hearth of the furnace. Y

1T. In the reduction of ore by smelt-ing in anelectric furnace of the stack type having horizontal main electrodes arranged in two pairs at right angles to each other and secondary electrodes at top and bottom, the process which consists in. maintaining a gravity-fed central column ofcarbonaceous' material forming a. resistance conductor between said secondary electrodes and passing a suitable current therethrough7 feeding the material for reduction downward by gravity at the sides of said central column, and passing a two-phasecurrent through the charge by way of said main electrodes.

18. In the reduction of ore by smelting in an electric furnace of the stack type having horizontal main electrodes and secondary electrodes at top and bottom, the process which consists in maintainingr a gravity-fed central column of carbonaceous material forming a resistance conductor between said secondary electrodes and passing a suitable current therethrough, feeding the material for reduction downward by gravity atthe sides of said central column and in communication therewith, passing a two-phase curceases -ore downward by ravity at the sides of said central column an in communication there- With, passing a suitable current through said central column by Way of said secondary electrodes to start the operation and to render said column incandescent to a suflicient height, maintaining suiiicient heat by passing suitable ycurrents through the charge by way of saidl main electrodes, and running 0H the iiuid metal from the subjacenthearth of the furnace. 4

20. In the reduction of ore by smelting in an electric furnaceof the stack type having 'horizontal main electrodes and secondary Aelectrodes at top and bottom, the process which consists in feeding downward by gravity acentral column of carbonaceous material forming a resistance conductor between said secondary electrodes, feeding the ore downward by gravity at the sides of said central column and in communication therewith, passing a suitable current through said central column by way of said secondary electrodes to start the operation and to render said column incandescent to a sufficient height, maintaining suflicient heat by passing suitable currents through the charge by way of said main electrodes, causing carbonio oxid gas' from said incandescent column to flow continuously into the ore and carbonic acid from the ore to flow continuously into the incandescent column for conversion into carbonic oXid, discharging the gaseous by-product at the top of the furnace,

and running oli' the fluid metal from the subjacent hearth.

EDIVARD R. lliLOlllvitnesses:

C. MCFARREN, S. McDoNALD. 

